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A330103
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Numbers whose prime-indices do not have weakly increasing numbers of prime factors, counted with multiplicity.
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15
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77, 119, 154, 217, 221, 231, 238, 287, 308, 357, 385, 403, 413, 434, 437, 442, 462, 469, 476, 533, 539, 551, 574, 581, 589, 595, 616, 651, 663, 693, 713, 714, 763, 767, 770, 779, 806, 817, 826, 833, 847, 861, 868, 871, 874, 884, 889, 893, 899, 924, 938
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OFFSET
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1,1
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COMMENTS
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A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
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LINKS
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EXAMPLE
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The sequence of terms together with their corresponding multisets of multisets begins:
77: {{1,1},{3}}
119: {{1,1},{4}}
154: {{},{1,1},{3}}
217: {{1,1},{5}}
221: {{1,2},{4}}
231: {{1},{1,1},{3}}
238: {{},{1,1},{4}}
287: {{1,1},{6}}
308: {{},{},{1,1},{3}}
357: {{1},{1,1},{4}}
385: {{2},{1,1},{3}}
For example, 385 has prime indices {3,4,5} with numbers of prime factors (1,2,1), which is not weakly increasing, so 385 is in the sequence.
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MATHEMATICA
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Select[Range[1000], !OrderedQ[PrimeOmega/@PrimePi/@First/@FactorInteger[#]]&]
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CROSSREFS
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The version where prime factors are counted without multiplicity is A330281.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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